Silicone breast implants have been used for breast enlargement and reconstruction after mastectomy since 1963. It is estimated that they have been implanted in over 2 million women in the U.S. The U.S. Food and Drug Administration (FDA) has required manufacturers of the implants to submit evidence of their safety and effectiveness. The implants have been shown to benefit women in psychological studies. Physical risks include capsular contracture (affecting up to half of wearers), impaired mammographic results, implant rupture, and possibly connective tissue disease. Human studies would benefit from improved research design, including controls and long-term follow-up. Professional societies of plastic surgeons, whose members benefit commercially from breast augmentation and reconstruction, have campaigned forcefully for the continued and increased use of breast implants by women.